Sputter help

[Sh0Enough]

I have been having some problems with my 92 MTX. The engine periodically sputters like a misfire or a timing problem. It runs very ruff and has no power. It's was to the point that you had to hold it to the floor when taking off to keep it from stalling. Then it would kick back in and launch lol. Sometimes it would be for an entire 30 minute trip, others it would spit on and off quickly. Seemed to be no rhyme or reason.

I put it in the shop and had the following items replaced.
-CPS
-plugs
-plug wires
-intake manifold gasket
-valve cover gasket
-water pump
-water pump gasket
-PCM
-cat-back exhaust
-tires

Some items not related but you can see why I'm not ready to give up yet.

This is what he sent me on the codes it spits after the sputter happens.

"code 114 act/ Iat / vat/ check out of range and 225 nok sensor not detected."

He doesn't think it's the nok sensor (not sure why) and want's to install a cam sensor next.

can anyone please offer me some guidance here. Has anyone had a similar problem? Is there a common failure that I am over looking?

 

[Sh0Enough]

We are no longer getting code 114, only 225 now. Is there any more info I can provide to help with this?

 

[bubba]

You either jumped timing or your knock senser is going out

 

[Sh0Enough]

You either jumped timing or your knock senser is going out

Thank you for the reply bubba.

I am hoping you are right about the nok sensor. That will be the next thing going in.

The miss comes and goes. The idle drops to ~500 bouncing up to 1000. it's very ruff and has no power. Then out of no where is stops missing it runs great... very smooth... loads of power... "normal"

If it jumped timing it would consistently miss right?

Update: cam sensor replaced. still having the same issue.

 

[elarm1]

I would swap DIS' with someone and see if that is your problem.

 

[bubba]

No problem man, I don't think it's the dis.....However have you cleaned IAC or maf?

Thank you for the reply bubba.

I am hoping you are right about the nok sensor. That will be the next thing going in.

The miss comes and goes. The idle drops to ~500 bouncing up to 1000. it's very ruff and has no power. Then out of no where is stops missing it runs great... very smooth... loads of power... "normal"

If it jumped timing it would consistently miss right?

Update: cam sensor replaced. still having the same issue.

 

[Sh0Enough]

RCM replied to my email with some suggestions...

"I'd check to be sure that you existing module is getting good ground at it's two lower mounting bolts, that the intake manifold crossover that it's bolted to is also getting good ground at it's two mounting bolts, and if it only acts up when hot I'd check that there's an even coating of heat-sink paste on the back of it (aids heat transfer).

A misfire could come from several other possible causes:

low fuel pressure
weak ignition- spark plugs
spark plug wires
coil pack
cam position sensor
crank position sensor
MAF sensor
Baro sensor
etc."

Fuel pressure would through a code right?

The DIS ground was one of the first things we cleaned.

I have addressed most everything else besides the MAF, Baro, Coil pack and IAC.

I will update once I clean the IAC and MAF

Thanks again guys

 

[itwonder]

The next time it happens, unplug the MAF and see if it runs better. It would be good to swap for a known good DIS module. Run a temporary ground wire from a DIS lower bolt to battery ground to make sure you have not missed something. Also swap the coil pack. You could also have a fuel pump on the way out. RCM's suggestions are right on.